The man who is arguably the nation's most controversial law enforcement official, Maricopa County Sheriff Joe Arpaio, was sued by the Justice Dept. Thursday for allegedly obstructing the federal agency's civil-rights investigation of his department, specifically its treatment of Hispanics.

The Justice Department's expressed it frustration with Arpaio in its news release on the lawsuit which was filed in U.S. district court in Phoenix. The agency said Arpaio's alleged unhelpfulness was the worst the agency had seen in three decades.

The department filed today’s lawsuit after exhausting all cooperative measures to gain access to MCSO’s documents and facilities, as part of the department’s investigation of alleged discrimination in MCSO’s police practices and jail operations. Since March 2009, the department has attempted to secure voluntary compliance with the department’s investigation. MCSO’s refusal to cooperate with the investigation makes it an extreme outlier and the department is unaware of any other police department or sheriff’s office that has refused to cooperate in the last 30 years.

“The actions of the sheriff's office are unprecedented. It is unfortunate that the department was forced to resort to litigation to gain access to public documents and facilities,” said Thomas E. Perez, Assistant Attorney General for the Civil Rights Division.

Arpaio has gotten national attention for his get-tough approach on illegal immigration and those arrested in his jurisdiction for any number of reasons.

As NPR's Carrie Johnson reported for the network's newscast:

He's been the focus of national attention for making inmates work on chain gangs, live in tent cities and wear pink clothes.

As part of their investigation that began last year, federal attorneys had asked Arpaio for access to arrest reports and other documents as they tried to determine if his department violated the rights of citizens and non-citizens alike through illegal searches and other practices.

The two sides had been going back and forth and the federal government obviously decided to force the issue.

For his part, Arpaio accused the federal government of having ulterior motives and jumping the gun.

Arpaio said the lawsuit, filed in U.S. District Court in Phoenix, is disappointing given that he and his office were cooperating on the federal probe. "I thought we were really close to getting this resolved," the sheriff said.

Arpaio restated his confidence that Maricopa County Sheriff's deputies do not target Hispanic citizens because of their race, and said if the Justice Department had any evidence of racial profiling, they wouldn't be suing him to get records to prove that deputies profile.